Methods in Oil Recovery Processes and Reservoir Simulation

Abstract

The exploitation of an oil field is a complex and multidisciplinary task, which demands a lot of prior knowledge, time, and money. A good reservoir characterization is deemed essential in the accomplishment of Enhanced Oil Recovery (EOR) processes in order to estimate accurately the properties of the porous medium affecting the flow properties. Several techniques at a field scale are currently being used to determine these properties, which are time and money consuming. But these alone do not guarantee the success of the project. Reservoir simulation and numerical techniques were then included in the pre-development and follow-up studies as an effective tool to determine the productivity and future behavior of the oil field. As the computational power increased, more advanced and detailed models were developed, including different chemical and physical phenomena. But alongside this process, there was an active research in the area of reservoir simulation, improving the accuracy and efficiency of the numerical schemes used for the flow, transport, and energy equations. The aim of this review is to address the topics described. Firstly, the origin of an oil recovery process, the economic factors and field tests involved are introduced. Secondly, the oil and porous medium origin and characterization as well as an introduction to the fundamental concepts and equations are associated to reservoir simulation. Finally, a brief description and analysis of the techniques are used in reservoir simulation employing finite difference methods, their downsides and possible ways to overcome these problems.

Numerical Modeling and Validation of a Novel 2D Compositional Flooding Simulator Using a Second-Order TVD Scheme

“…In order to address this issue, a scheme with a higher order of convergence was derived, both in time and in space. This scheme has a TVD flux limiting functions so as to prevent numerical diffusion and dispersion phenomena, and therefore the occurrence of spurious oscillations, commonly found in traditional Finite Difference Method schemes [5]. The combination of the compositional approach with the second numerical discretization has resulted in a novel and complete simulator, which can be used for the design and screening of new chemical species to be used in EOR.…”

“…As time goes on, and the reservoir is exploited, the pressure decreases resulting in a porosity reduction. Similarly, in deeper formations the overburden pressure increases hence the porosity is reduced [5,34,35]. The numerical technique adopted for the resolution of these equations is the IMPEC method, which calculates pressures implicitly and concentration for each of the component explicitly.…”

“…However, thus far the system presents only 13 equations (Equation (1) for each phase, capillary pressure relationship, Equation (4) for two components, Equation (6) for each component, Equations (7), (8) for each phase, Equation (9), and Equation (11)). The remaining equations to determine the system, equal to N comp · N phase − 1 , are obtained from algebraic relationships between the volumetric concentrations of the components on the phases [5]. These describe the phase behavior, of which its understanding and correct modeling is a vital concept in chemical EOR processes.…”

“…Primary recovery uses natural driven mechanisms present in the porous medium; then, water is injected in order to repressurize the medium as well as to sweep the remaining oil to the producer wells. It is usually considered that after these two stages around 45% to 55% of the original, oil in place is still trapped underground [5]. This fact, along with the increasing demand of energy and the decreasing number of new fields being discovered, has led researchers and industry to look for ways to increment the efficiency of existing fields.…”

Application of Smoothed Particle Hydrodynamics (SPH) to Flow Simulations in Oil Reservoir Rocks

“…Among these, the use of numerical simulations has become a useful tool to complement traditional type experiments for a large number of phenomena occurring during oil extraction operations. [2][3][4][5][6] Numerical models aimed at solving oil extraction problems involve mainly the solution of the nonlinear fluid equations for multiphase and multicomponent flows through a heterogeneous medium (porous rock). 3,[7][8][9] When describing the flow at a microscopic level (or pore scale), the Navier-Stokes equations coupled to the mass conservation law for multiphase flow must be solved, while at a macroscopic level Darcy´s law is employed in place of the Navier-Stokes equations to describe the flow behavior.…”